Bioacoustics of Caracladus avicula

Description . Male (NMBE Ar 5292): Total length 2.02 mm . Cephalothorax: honey brown (138 U); reticulated; 0.84 mm long without cephalic lobe, 1.19 mm long with cephalic lobe, 0.71 mm wide. Cephalic lobe: light brown (124 U); Thaler (1969) describes this lobe as slim elongated shaft which is sloped forwardly, originating at the position of the median eyes ( Fig. 23 ), with a hairy tip that is laterally compressed ( Fig. 21 ); smallest diameter below the eye-field 0.06 mm wide laterally, 0.07 mm wide dorsally; ventral side of the shaft with channel-like depression bearing a sulcus ( Thaler 1969 ), margin of sulcus 0.16 mm below the AME ( Fig. 22 ). Eyes: PME dorsally on tip of lobe; AME projecting forward from the shaft ( Fig. 23 ); one long macroseta projecting forward between AME ( Fig. 23 ). Clypeus: directed obliquely backwards ( Fig. 23 ). Sternum: very fine brown (469 U) pigmentation on yellow (124 U) ground, dark brown (469 U) on the margins; 0.47 mm long; 0.47 mm wide. Chelicerae: light brown (124 U); stridulatory striae fine and dense ( Fig. 13 ); promargin with five big teeth; retromargin with five denticles. Legs: yellow (120 U); tibia I–IV with one dorsal proximal macroseta (1-1-1-1), 1.3–1.6 times longer than diameter of tibia; Tm I: 0.58 mm . Pedipalp: yellow (120 U); patella cylindrical; tibia nearly two times longer than broad, with glabrous band retrolaterally ( Fig. 20 ), dorsal with highly sclerotised small tip facing forward ( Fig. 20 ); paracymbium simple clasp ( Fig. 17 ); tegulum distal with short and long papillae on protegulum ( Figs 17, 18 ); suprategulum kneed; column broad; marginal suprategular apophysis present ( Thaler 1969: Figs 17, 18 ); distal suprategular apophysis pointed ( Thaler 1969: Figs 17, 18 ); embolic membrane slender; radix simple without any processes other than the short radical tailpiece and the strongly sclerotised, slim, terminal, whip-like embolus ( Figs 18, 19 ). Abdomen: dorsal olive green to brown (125 U), ventral darker (117 U); booklung covers brown (125 U), scaly ( Fig. 15 ). Female (NMBE Ar 5315): Total length: 1.79 mm . Cephalothorax: honey brown (138 U); broad eggshaped ( Thaler 1972 ); 0.77 mm long, 0.62 mm wide. Eyes: eye-field steep ( Thaler 1972 ); posterior eyes separated by their diameter; AME separated by their radius. Clypeus: concave. Sternum: very fine brown (469 U) pigmentation on yellow (124 U) ground, dark brown (469 U) on the margins; 0.47 mm long; 0.47 mm wide. Legs: yellow (122 U); tibia I–IV with one dorsal proximal macroseta (1-1-1-1), 1.4–1.8 times longer than diameter of tibia; Tm I: 0.56. Chelicerae: light brown (124 U); promargin with five teeth; retromargin with five denticles; stridulatory striae indistinct and scaly. Epigyne: rectangular dorsal plate visible in ventral view; receptacula laterally to dorsal plate, visible in transparency trough ventral plate ( Fig. 26 ). Vulva: copulatory pouch narrows in the middle of the vulva forming a copulatory duct ( Figs 26, 27 ); receptacula globular, incoming dorsally. Abdomen: dark olive green to black (147 U). Tracheal system with two thick median and two thin lateral tracheae ( Fig. 25 ). Variation. The measurements are based on specimens from the NMBE (Ar5281, Ar5290, Ar5292, Ar5298, Ar5304, Ar5315, Ar5318, Ar5324, Ar5329, Ar5352, Ar5356: 6♂ 6♀ ) and the NB (P-G 1-4 H, P-G 1- 4 I , coll. Zingerle: 4♂ 3♀ ). Males (n=10, means in brackets): The coloration is variable. Total length 1.95–2.31 mm ( 2.10 mm ). Cephalothorax: 0.76–0.89 mm ( 0.82 mm ) long without cephalic lobe, 1.10–1.26 mm ( 1.17 mm ) long with cephalic lobe, 0.65–0.71 mm ( 0.69 mm ) wide. Cephalic lobe: smallest diameter below the eye-field 0.06–0.07 mm ( 0.06 mm ) wide laterally, 0.06–0.08 mm ( 0.07 mm ) wide dorsally; margin of sulcus 0.12–0.16 mm ( 0.14 mm ) below the AME. Legs: dorsal proximal macroseta on tibia 1.3–1.6 times longer than diameter of tibia ( Thaler 1969 ); Tm I: 0.50–0.61 mm ( 0.56 mm ). Females (n=9, means in brackets): The colorations are variable. Total length: 1.68–1.91 mm ( 1.80 mm ). Cephalothorax: 0.77–0.84 mm ( 0.81 mm ) long, 0.62–0.67 mm ( 0.65 mm ) wide. Legs: dorsal proximal macroseta on tibia 1.4–1.8 times longer than diameter of tibia; Tm I: 0.53–0.60 mm ( 0.57 mm ).